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    <script>
        //【1】定义变量并且覆盖重写它
        var numberl = 5;
        numberl = 3;

        console.log(number1); //
        //【2】运算符操作他们
        number1 = number1 + 5;
        // 3 + 5 = number1 = number1 - 6;
        // 8 - 6 = var number2 = number1 * 10;
        // 2 (times) 10 = 20var number3 = number2 / number1; 
        // 20 (divided by) 2 = 1
        //【3】加号运算符还能够将字符串拼接起来
        var myString = "I am a " + "string!"; // "I am a strin
    </script>
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